Electrical outlet box with polygonal mounting bore

Abstract

An electrical outlet box formed of nonmetallic material which has a pair of integral bosses that angularly align, engage and retain wiring device mounting screws therein. The bosses each have a through bore for receiving the screws comprising in sequence a frustoconical surface, a cylindrical surface having a diameter slightly larger than the crest diameter of the mounting screw threads, and a self-tapping surface defining a regular hexagon in transverse cross section. The hexagon has a diameter across its corners slightly larger than the crest diameter of the screw threads, and a diameter across its flat sides slightly larger than the root diameter of the screw threads and slightly smaller than the crest diameter of the screw threads.

What is claimed is: 
     
       1. An electrical box for supporting a device by an externally threaded screw, the screw having threads with a crest diameter and a root diameter, comprising: a boss integrally formed with the box and having a front face; and   a straight self-tapping bore extending inwardly of said boss from said front face for receiving the screw, said bore having a substantially regular polygonal cross-sectional configuration with an even number of sides, said bore having a first diameter across corners of said polygonal configuration slightly larger than the crest diameter of the screw threads, and a second diameter across flat sides of said polygonal configuration slightly smaller than the crest diameter of the screw threads and slightly larger than the root diameter of the screw threads.   
     
     
       2. An electrical box according to claim 1 wherein said polygonal configuration is hexagonal. 
     
     
       3. An electrical box according to claim 2 wherein said first diameter is about 0.166 inch; and said second diameter is about 0.145 inch. 
     
     
       4. An electrical box according to claim 2 wherein said first diameter is 0.166 inch±0.002 inch; and said second diameter is 0.145 inch±0.002 inch. 
     
     
       5. An electrical box according to claim 2 wherein said first diameter is about 0.140 inch; and said second diameter is about 0.099 inch. 
     
     
       6. An electrical box according to claim 2 wherein said first diameter is 0.140 inch±0.002 inch; and said second diameter is 0.099 inch±0.002 inch. 
     
     
       7. An electrical box according to claim 1 wherein said cross-sectional configuration is constant along a first axial length of said bore. 
     
     
       8. An electrical box for supporting a device by an externally threaded screw, the screw having threads with a crest diameter and a root diameter, comprising: a boss integrally formed with the box and having a front face; and   a straight self-tapping bore extending inwardly of said boss from said front face for receiving the screw, said bore having, in sequence from said front face, a downwardly and inwardly tapered, substantially frustoconical surface,   a cylindrical surface coaxial with said frustoconical surface and having a diameter at least substantially equal to the crest diameter of the screw threads, and   a substantially regular polygonal cross-sectional configuration, said polygonal configuration having an even number of sides.     
     
     
       9. A nonmetallic box according to claim 8 wherein said bore has a first diameter across corners of said polygonal configuration slightly larger than the crest diameter of the screw threads, and a second diameter across flat sides of said polygonal configuration slightly smaller than the crest diameter of the screw threads and slightly larger than the root diameter of the screw threads. 
     
     
       10. A nonmetallic box according to claim 8 wherein said cylindrical surface and said polygonal cross-sectional configuration define at the interface a shoulder. 
     
     
       11. A nonmetallic box according to claim 8, wherein said shoulder is planar and lies in a plane substantially perpendicular to an axis of said cylindrical surface. 
     
     
       12. A nonmetallic box according to claim 1 wherein said bore comprises, adjacent said front face, a downwardly and inwardly tapered, substantially frustoconical surface. 
     
     
       13. An electrical box for supporting a device by an externally threaded screw, the screw having threads with a crest diameter and a root diameter, comprising: a boss integrally formed with the box and having a front face; and   a straight self-tapping bore extending inwardly of said boss from said front face for receiving the screw, said bore having a substantially regular polygonal cross-sectional configuration and a cylindrical surface between said front face and said polygonal cross-sectional configuration, said cylindrical surface having a diameter at least substantially equal to the crest diameter of the screw threads.   
     
     
       14. A nonmetallic box for supporting a device by a threaded screw having screw threads with a crest diameter and a root diameter, comprising: a boss integrally formed with the box and having a front face and a rear face; and   a through bore extending between said faces for receiving the screw, said bore including in sequence from said front face to said rear face, a downwardly and inwardly tapered, substantially frustoconical surface,   a substantially cylindrical surface coaxial with said frustoconical surface and having a diameter at least substantially equal to the crest diameter of the screw threads, and   a set of planar surfaces coaxial with said cylindrical surface essentially defining a regular polygon in transverse cross section with an even number of sides and having a first diameter across corners of said polygon slightly larger than the crest diameter of the screw threads and a second diameter across flat-sides of said polygon slightly smaller than the crest diameter of the screw threads and slightly larger than the root diameter of the screw threads.     
     
     
       15. A nonmetallic box according to claim 14 wherein said regular polygon is a hexagon. 
     
     
       16. An electrical box for supporting a device by an externally threaded screw, the screw having threads with a crest diameter and a root diameter, comprising: a boss integrally formed with the box and having a front face; and   a straight self-tapping bore extending inwardly of said boss from said front face for receiving the screw, said bore having a plurality of discrete, inwardly extending projections separated by spaces, said spaces being defined by inwardly facing surfaces defining a first diameter slightly larger than the crest diameter of the screw threads, innermost surfaces of said projections defining a second diameter slightly smaller than the crest diameter of the screw threads and slightly larger than the root diameter of the screw threads, said bore also including a cylindrical surface between said front face and said projections, said cylindrical surface having a diameter at least substantially equal to and only slightly larger than the crest diameter of the screw threads such that said cylindrical surface holds the screw in coaxial alignment with said first and second diameters.   
     
     
       17. An electrical box according to claim 16 wherein said projections are flat sides of a bore portion having a substantially regular polygonal cross-sectional configuration; and said spaces are corners of said polygonal cross-sectional configuration. 
     
     
       18. An electrical box according to claim 17 wherein polygonal configuration is hexagonal. 
     
     
       19. An electrical box according to claim 16 wherein said cylindrical surface has an axial length of about 0.110 inch. 
     
     
       20. An electrical box according to claim 16 wherein said cylindrical surface has a transverse diameter of about 0.140 inch. 
     
     
       21. An electrical box according to claim 16 wherein said cylindrical surface has a transverse diameter of about 0.116 inch.